Articficial Selection Lab

Introduction

This lab is a test of our abilities to maintain an experiment over a long period of time, while collecting proper research to utilize in our data, analysis, and conclusion. Artificial selection is a process that takes a moderate amount of time to carry out, as the plants need to grow, then must be artificially mated by hand.

Purpose

This lab was meant to demonstrate artificial selection among specific breeds of Fast Plants by having students breed their own line of plants with artificially selected traits.

Procedure

Plant the P parent generation:

1. Thread a wicking cord through a hole in the bottom of each pot.

2. Fill each pot with a light planting mix and pack gently but firmly into the pot until it is nearly full. Ensure the wicking cord sticks up through the top of the planting mix.

3. Plant three seeds in an appropriately labeled pot. Spread the seeds evenly on top of the planting mix.

4. Cover the seeds with a light layer of soil.
5. Place the pots in the grow area, making sure the wicking cord enters down into the fertilizer water reservoir.
6. Water plants once after placing them in the grow area, and continue to water plants once or twice a day every day.

7. Take photographic evidence of growth, as well as measurements of the development of growth and/or a specific trait on the plant.

Planting the F₁ generation:

1. When plants have become fully grown, pollinate them by hand to produce seeds for the specific trait you would like to produce in the F₁ generation.
2. Wait for plants to form seed pods, continue observing growth and recording data, as well as regularly watering the plants.
3. Once seed pods are fully formed, remove them from the plant and set them out to dry.
4. Once dry, open the pod and plant the seeds in a new set of pots using the same steps used to plant the P parental generation of plants
5. Observe this F₁ generation, record growth, and conclude if your artificial selection produces the phenotype you were attempting to achieve.

Data

Day 0

Planting the Plants

Day 1
No progress. Made sure plants had enough water and added about 20mL of water to each pot.

Day 2

No change. It's Friday, this is the first weekend the plants will be without a daily watering from us.

Day 5

Harry has some growth. A small sprout is growing very close to the wicking cord. Quinta and Bendita are showing no signs of growth. Other groups in our class have had more success, some pots have two sprouts that are about half an inch tall. I have noticed that second period’s plants are doing better as a whole compared to our period. Most pots have all three plants growing by now. I'm starting to wonder if the amount of dirt we out into our pots is too little, or if some other condition is preventing Bendita and Quinta from growing. Will try to water the plants more frequently.

Day 6

Quinta and Bendita have some growth! Harry has also grown some more! After school I realized that the growth in Bendita died. I may have accidentally drowned it yesterday after school when I was watering the pots. By day 12 we should be seeing flowers, but I'm not sure how well that's going to go. As of right now, second period’s plants are doing much better than ours. I think that is because their light is brighter, but also, there seems to be some sort of extra insulation with being on a lower level. These science rooms can be pretty cold.

Day 7

Day 8

Day 12

Harry has had nice growth, Quinta died, Bendita is coming along

Day 14

Day 15

Quinta is dead and gone. Bendita and Harry are doing okay. Bendita seems that she is starting to sprout a flower.

Day 18

Flower buds present on Bendita and Harry. Harry actually has three sprouts.

Day 19

Harry has many plants and many buds, Bendita has one plant and a few buds, Quinta is still dead.

Day 22

Harry is ready to pollinate

Day Unknown:

Plants are dead

Second Attempt at Life:

A new life brings a vast array of possibilities. Our hopes are high for this new generation.

Never mind, our second attempt also is dead.

Lesson Learned: none of us should become gardeners

Analysis

From our Plant Diary below, it can be concluded that we were never able to successfully grow plants/sustain their lives long enough to have them reproduce. This could have been due to environmental conditions (such as the intensity of the light, the temperature of the room, and the amount of fertilizer water in the basin below them) or our own inept gardening abilities. While it is very unlikely that nearly everyone in our class had their plants die during the same exact weekend by chance or because we all are terrible plant caretakers, it is possible. Comparing our plants to the other class, we noticed that theirs were healthy and growing (buds that matured to flowers was witnessed) versus our plants which had none to very little growth. This leads us to believe that the issue of why our plants failed to grow was due, more so, to environmental factors.

Conclusion

Since we had not one, but two failed generations of plants, we were never able to see the fruits of our labor (or the hairy stems of our labor, rather). Ideally, we would have witnessed artificial selection. It would be similar to what Gregor Mendel did back in the 1800s. Artificial selection involves selectively choosing which traits are in the gene pool of a population. The plants with the desired traits will be allowed to reproduce to increase the amount of desired traits in the gene pool. Those traits that we want to exclude from the gene pool would be reduced in quantity. Eventually, only plants with the desired traits would be present. Plants reproduce through pollination, so what should have been done is pollen from plants with the desired traits would be used to pollinate other plants so that their offspring carry alleles that code for desired traits. Those traits may or may not be expressed in the offspring, so those plants that do express the trait will be used to reproduce. We can also cross different genes to potentially create plants with unique combinations of traits. In our F1 generation, we should have seen that our purple stem hairy, non purple stem hairless, and non purple stem yellow green leaf to have grown until cross pollination was possible. Then, picking out our desired traits, we should have seen our desired traits replicated in the F2 generation.